The potent anticarcinogenic effects of phenolic antioxidants 2(3)-tert- butyl-4-hydroxyanisole (BHA), and its demethylated active metabolite 2(3)-tert-butylhydroquinone (tBHQ), are partly attributed to potent induction of some phase 2 drug metabolizing enzymes such as glutathione S-transferases (GST), NAD(P)H: quinone oxidoreductases (NQO) and UDP-glucuronosyltransferases (UGT). However, the molecular mechanisms by which BHA and tBHQ induce phase 2 detoxifying enzymes, a potential chemopreventive action, have not been characterized. Recent studies from our laboratory and others have shown that the activity of a cellular signaling molecules, the mitogen-activated protein kinases (MAPKs), extracellular regulated kinase 2 (ERK2), c-Jun N-terminal kinase 1 (JNK1), or p38 can be enhanced by BHA and tBHQ, in a time- and dose-dependent fashion. The observations that modulation of one or more of these MAP kinase pathways by genetic or biochemical approaches, altered the level of expression of phase 2 NQO enzyme activity led us to propose the hypothesis that phenolic compounds such as BHA induce MAPK signaling pathway leading to phase 2 gene induction. The following specific aims are designed to test this hypothesis. (1) Determine the dose-dependent effect of BHA administration on the in vivo activation of MAPK and induction of phase 2 genes expression in mouse livers. (2) Determine the activation of MAPK pathways in hepatoma cell lines and in primary cultured of human and mouse hepatocytes in BHA-induced phase 2 NQO gene induction. (3) Determine the activation of transcription factor Nrf2 by MAPK pathways in BHA-induced phase 2 NQO gene induction. (4) Determine the phosphorylation of Nrf2 in BHA-induced phase 2 NQO gene induction. The results of our work will likely provide new information on (i) the role of signal transduction events in the regulation of phase 2 NQO gene expression by phenolic antioxidants such as BHA, and (ii) identification of the signaling pathway components that can be useful as chemopreventive agent design and screening targets.